Surf boards and body boards have been known for a long time and are in extensive use along the seashores and coasts throughout the world. Recently, the so-called body boards have become popular and are used in great numbers by young and old for fun at the beach. In addition, even more recently, professional body boarding and amatuer body boarding contests have been established throughout the world and refinements of body board designs and riding techniques have been developing rapidly.
Unlike surfing, where a rider stands upright on a relatively long and narrow surf board, a body board is a relatively short, blunt-nosed wide board on which the rider lies down with his torso on the board and holds the sides or top of the board for riding the surf onto the beach. In general, riding a body board requires considerably less skill than surfing and is therefore amenable to the participation of people of all ages.
Unlike a surf board, a body board is relatively sluggish in response to body movements intended to steer the board in the water. A standing surfer can lean in the direction he wants to steer and is also free to step forward or backwards on the board to obtain a desired response from his board. On the other hand, a rider of body board does not have this freedom of movement. The rider generally lies down with his chest or pelvis on the board and grasps the sides or forward end of the board with both hands for the purpose of staying on the board. Thus, the steering of the board must be achieved by shifting the rider's weight by rolling or sliding his body on the board.
To turn the moving body board, one rail of the board must be pushed downward into the water so that more of the rail of the body board is placed in contact with the water. The surface tension of water moving along the bottom and rail of the board causes the water to attempt to adhere to the rail of the body board. The increased surface area of the body board placed in contact with the water, in combination with the effect of the adhesion of the water to the rail of the body board causes increased resistance or drag in the water on the side of the board pushed down into the water, which, in turn, pulls the board in that direction. To angle the board relative to the water, the rider presse down against the side of the board with his forearms or elbows to create the desired resistance or drag of the board in the water which slows down that side and turns the board. Leaning or shifting the rider's weight to the left turns the board to the left, and conversely, leaning or shifting the rider's weight to the right turns the board to the right. The harder one leans, or in other words, the more weight one places on the furthest leverage arm of the central line of the board, the more resistance is created, and in turn, the faster the board turns.
In order to facilitate or accentuate the turns, a rider sometimes slides from side to side along the board in order to assist the shifting of his weight or up and down along the board to modify his drag and balance in the water. In particular, the board travels faster when weight is distributed toward the front of the board thereby eliminating the drag of the rider's legs in back of the board. Thus, in order to control speed it is necessary to be able to shift a rider's weight forward and backward for various maneuvers.
The prior art body boards have a top surface which is generally smooth allowing the rider to freely slide on the board's surface. However, in certain situations such as tight turns and other fast maneuvers, it is desirable to maintain a reasonable amount of traction on the board. None of the surfaces of the prior art provide a surface which is selectively slippery or resistant depending upon the rider's need and body positioning.
Also, with the advent of advanced riding techniques, the more skilled riders have expressed a need to achieve faster speeds than are currently being achieved using the prior art body board designs. In this connection, the side rails of most of the present body board designs are shown in FIG. 7 of the drawings, are set at an obtuse angel .theta. relative to the horizontal hull plane. As a result of this shape, the body boards passes through the water with a certain resistance due, in part, to the path of the water which adheres to the diagonal rail as it cuts through the water. The adherence of the rail causes the board to travel at a relatively slow speed to the water because its contact with the water along its long surface area creates resistance on the board through the water.
The foregoing problems are overcome by the present invention described in brief below.